The present invention relates to a mouthpiece for inhalation therapy devices used by oxygen dependent patients.
The delivery of medicines to patients by inhalation therapy is an important treatment for many illnesses. Some patients who benefit from such a therapy require a constant supply of oxygen in order to maintain a sufficient level of oxygen in their blood. For various reasons, devices for delivering medicines for inhalation therapy use air to carry the medicine in the patient""s respiratory air flow. Thus, such therapy interrupts the supply of oxygen to the patient which can lead to negative clinical symptoms such as dizziness, tightness and fainting, due to the decrease oxygen level in the blood. Inhalation therapy typically lasts as long as twenty minutes, and interruption of the oxygen supply for that long will result in a rapid decrease in the level of oxygen in the blood for such patients. Patients who typically require high levels of oxygen in their inspiratory air flow include those suffering from pulmonary hypertension and COPD. It is clinically important to maintain the correct levels of oxygen in the blood of such patients, and also to deliver the appropriate drugs effectively and quickly.
To fully appreciate the effect of interrupting the oxygen supply to pulmonary hypertension patients, graphs are shown in FIGS. 1 to 6 which show the drop in arterial oxygenation. In FIG. 1, a graph shows an initial arterial oxygenation level of nearly 90% at the time of interrupting the oxygen supply to the patient. From that time, the patient is breathing air instead of oxygen. As will be seen, the level of oxygenation drops extremely to just over 80%. On restarting the supply of oxygen to the patient, the arterial oxygenation level increases quite quickly to a level of about 87% before beginning a more gradual ascent towards the oxygenation level present before treatment started.
FIG. 2 is a graph showing the mixed venous oxygenation of a patient during the same experiment as is shown in FIG. 1. The oxygenation starts at about 52% when the oxygen supply is interrupted and replaced with air. The oxygenation level drops steadily during the ten minutes of the oxygen interruption to about 44%. Once oxygen supply to the patient is restarted, the oxygenation level increases only gradually.
In order to indicate just how serious this reduction in oxygenation of the blood has on the patient, the FIG. 3 shows a graph of the mean pulmonary artery pressure over the period of the experiment shown in FIGS. 1 and 2. As will be seen, as soon as the oxygen supply is withdrawn from the patient and replaced with an air supply, the pressure increases from about 54.5 mmHg to about 58 mmHg. In the patients suffering from ailments such as pulmonary hypertension and COPD, such an increase is clinically extremely undesirable and can make the symptoms worse.
It is, therefore, desirable to deliver a sufficient level of oxygen in the respiratory air flow of a patient while at the same time delivering a drug into the air stream of a patient for inhalation.
DE 19755600 A1 and EP 0855224 A2 disclose jet nebulizers which use compressed air supplied by a compressor or compressed air cylinder, to produce an aerolized medicine. If operating in conjunction with a compressed air cylinder, it is possible to use compressed oxygen instead of air. This allows the inhalation gas to be partially enriched with oxygen. However, the compressed gas which causes atomization contributes only a small part of the gas stream leading to the patient during inhalation. However, this also necessitates an appropriate oxygen pressure pipe or a compressed oxygen canister with a pressure-reducing valve mechanism which is usually only available in a few hospitals, medical practices or clinics. In fewer patients who have the necessary equipment at home, the ability to treat patients at home is important to maintain patients"" standard of living and to maintain treatment at lower cost.
In theory, this problem could be solved by inhalation inside an oxygen tent. The gas entering the nebulizer would then be oxygen, and the patient would then receive the required level of oxygen. However, the application of this solution is considerably limited by the unwieldy nature of such a tent. It should be appreciated here that the vast majority of gas inhaled by a patient using such a nebulizer is ambient air drawn into the device during inhalation.
EP 0933138 discloses ultrasonic nebulizers which use an ultrasonic field to atomize the medicine, the medicine then being carried in aerosol form in a stream of air being inhaled by the patient. Most require an external gas flow to discharge the produced aerosol. The oxygen tent could again be used to enrich the aerosol inhaled with oxygen, but with the resultant disadvantages. Another possibility would be to introduce an appropriate volume of oxygen into the ultrasonic chamber, but this would entail a continuous aerosol discharged both during inhalation and exhalation which substantially reduces the efficiency of the aerosolizing process. Much drug, may be as much as 80% to 90% would then be wasted.
DE 19801545 discloses how advancement in mouthpiece design do not address the possibility of providing continuous oxygenation during inhalation.
According to the present invention, a combination mouthpiece for inhalation therapy devices, is arranged to supply both a stream of air carrying an aerosolized drug and oxygen, and has a body defining an aerosol duct through which, in use, the stream of air carrying the aerosolized drug is supplied to a patient during inspiration, an inlet hole through the body for receiving in a releasable and secure manner an oxygen tube adapter, characterised by at least one partition within the body defining at least one oxygen duct, the oxygen duct being in a form such that it extends generally parallel with the aerosol duct and has a flow cross-section sized in order to guide a suitably large oxygen stream from the oxygen tube adapter through the inlet hole to the patient. In this way oxygen dependent patients can receive inhaled therapy treatment and oxygen rich gas for inhalation so as to maintain the oxygen levels in the blood while still delivering the appropriate drug.
Further aspects of the invention, as well as preferred features of the present invention are referred to in the claims.